Shower doesn't drain

plumbing, drainage and waste water questions here please

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mundungus
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Shower doesn't drain

Post by mundungus »

Hey All,

The the shower in the ensuite doesn't drain well, and hasn't done since it was installed. I thought it was just blocked, but have tried multiple unblocking fluids including bleach. The basin next to it seems to drain okay.

See attached pics of how close it is to the basin, and how close the basin is to the toilet. The grey circular thing next to the toilet is an air admittance valve. I replaced the air admittance valve, assuming it was faulty, but that hasn't fixed the problem.

The plumbing is from the shower direct into a T piece where it connects to the basin, then into an adapter to the soil pipe T piece that the toilet connects to, then into another soil pipe T piece for the valve. The soil pipe exits under the valve. So quite simple plumbing.

The other day I did something different, I flushed the toilet whilst the shower tray was full of water, and suddenly the shower drained straight away.

So now I'm realising that it isn't blocked, it just cant get air behind it to drain. I'm thinking that the shower water just doesn't create enough of a vacuum to operate the valve like the toilet does.

As the floor is tiled and I really don't want to have to cut a hole in the ceiling downstairs if I can avoid it. I'm thinking of putting a small air admittance valve under the basin (a waste pipe sized one).

Do you think that would solve the problem?
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dewaltdisney
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Shower doesn't drain

Post by dewaltdisney »

I wonder if you unscrew the basin bottle trap and run the shower if that works. You will then prove the basin pipe AAV solution. :thumbright:

DWD
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mundungus (Tue Jun 16, 2020 5:03 pm)
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mundungus
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Shower doesn't drain

Post by mundungus »

I'm a dumbass, I have no idea why I didn't think of that.

Thanks DWD
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dewaltdisney (Tue Jun 16, 2020 3:41 pm)
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Bob225
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Shower doesn't drain

Post by Bob225 »

I can see the issue your air admittance valve beside the toilet seem to low to me or its getting stuck closed

stupid question but you do clean the shower trap out ? the centre part should lift out (some unscrew)

if not, As above put in an air admittance valve onto the sink waste (aka a Durgo)
mundungus
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Shower doesn't drain

Post by mundungus »

Thanks guys.

Yes, so unscrewing the trap seems to work, so just ordered AAV from Screwfix.

Yes, trap is clean. I had that out, and cleaned it before trying all the chemicals. So couldn't work out why it still seemed to be blocked.
fin
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Shower doesn't drain

Post by fin »

dunno how right i am..... are the aav's not supposed to be above the level of the highest up waste trap so in this case the basin waste?
ahfix
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Shower doesn't drain

Post by ahfix »

fin wrote:
Tue Jun 16, 2020 9:44 pm
dunno how right i am..... are the aav's not supposed to be above the level of the highest up waste trap so in this case the basin waste?
I thought that too
ahfix
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Shower doesn't drain

Post by ahfix »

I fitted a Avv bottle trap a while back due to awful gurgling from the bath when the basin drained. Not sure if it helps in this scenario.

ah
fin
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Shower doesn't drain

Post by fin »

ahfix wrote:
Tue Jun 16, 2020 9:47 pm
fin wrote:
Tue Jun 16, 2020 9:44 pm
dunno how right i am..... are the aav's not supposed to be above the level of the highest up waste trap so in this case the basin waste?
I thought that too
it would be simple enough for the poster to try. 1 meter length of soil pipe and a connector and a aav to raise that one up a tad
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